#include <iostream>
#include <string>
#include <cmath>

using namespace std;

bool isPrime(int num)
{
	if (num <= 1)
	{

	}
	for (int i = 2; i <= sqrt(num); i++)
	{
		if (num % i == 0)
		{
			return false;
		}
	}
	return true;
}

int main()
{
	string words[] = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };
	string input;
	getline(cin, input);
	int num = 0;
	for (int i = 0; i < 3; i++)
	{
		int word_index = -1;
		for (int j = 0; j < 10; j++)
		{
			if (words[j] == input.substr(i * 5, 5))
			{
				word_index = j;
				break;
			}
		}
		if (word_index == -1)
		{
			cout << "Wrong input" << endl;
			return 0;
		}
		int next_prime = num;
		while (true)
		{
			if (isPrime(next_prime))
			{
				cout << next_prime << endl;
				break;
			}
			++next_prime;

		}
		return 0;
	}
}
